ds250 stalls while driving

Hello i have a 2007 ds250 who suddenly stopps when driving With no warning, just cuts suddenly……
When then trying to start it`s all ok and can drive for several kilometers.
I think it must be a ignition fail, for example the CDI box???
I have never checked for spark because it allways starts directly aftervards……. -any tips?:th_smiliewavey: